The present invention pertains to a collapsible, structural member comprising a plurality of rigid segmental sections and a tensionable cable for compressing the sections together to provide a rigid structural member. More particularly, the present invention pertains to a structural member having connecting means on the end portions of the segmental sections for permitting adjacent sections to move axially with respect to each other from a maximally spaced-apart relationship wherein the structural member can be coiled to an abutting relationship when the segmental sections are under compression by the tensioning cable wherein the structural member is made rigid.
The present invention also pertains to a portable, collapsible shelter comprising a flexible cover secured to a plurality of structural members according to the invention.
The present invention further pertains to a composite structural beam comprising a plurality of cooperating individual structural members according to the invention.
In constructing collapsible structural members, emphasis has been placed on providing members that may be assembled and disassembled rapidly to conserve time and labor. Equal emphasis also has been placed on providing collapsible members that will occupy less space when they are to be shipped and/or stored in their collapsed condition.
A knock-down structural member is known from U.S. Pat. No. 2,874,812 which shows a plurality of thin-walled sections linked in end-to-end relation by a tension cable. Each section is hermaphroditic and accordingly has a projection at one longitudinal end and a hollowed-out portion or boss at the other end. Both the projection and the boss portions have central apertures for accommodating a tension cable therethrough.
To form an arch, U.S. Pat. No. 2,874,812 discloses a spacer element provided between the adjacent sections. The spacer elements likewise have a central opening to accommodate the cable. Each spacer element also includes a first face portion having a boss for receiving the projection of one section and an opposite face portion having a projection for interfitting with the boss of the other adjacent section. The spacers are wedge-like to enable the same elemental sections employed in producing a straight structural member to be utilized with the same cable to form a curved arch member.
U.S. Pat. No. 4,284,094 to Behrend discloses a tent structure with support arches and a roof skin. Each support arch is composed of individual rigid arch elements comprising two parallel tubes held together by distance pieces. The distance pieces are constructed as interfitting half shells and tubular sections. In adjacent arch elements, the half shell of one arch element receives the tubular section of the other arch element. One bracing wire is received through each parallel tube to erect the arch.
In an alternative embodiment, the arch elements of U.S. Pat. No. 4,284,094 are connected by means including two opposing boxlike structures, one at each interfitting end of two adjacent arch elements. A rubber block provides an elastic buffer between the rigid arch elements. In still another embodiment, a pair of spiral springs provide spacing means for interconnecting the arch elements.
U.S. Pat. Nos. 1,509,881; 2,345,377; 2,574,241; 3,006 670; 3,122,152; 3,150,670; 3,708,944; 3,857,213; 3,973,370; 4,140,141; and 4,152,875 disclose various other collapsible structures or structures having members held together by cables or the like.